* add system.setenv
* document system.setenv
* system.setenv: use wide versions of functions on windows
* do not include processenv.h
* system.setenv: report failure, including of utfconv
* system.setenv: free utfconv output
When `time_to_wake` was <= 0, so when a coroutine needed to be executed
as soon as possible, we didn't check for events, so we only performed a
`core.step` with the blink timer.
This resulted in jerky reactions to input.
Chloé Vulquin
Guldoman
Takase
Jan200101
jgmdev